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Diffstat (limited to 'drivers/md/dm-snap.c')
-rw-r--r--drivers/md/dm-snap.c23
1 files changed, 18 insertions, 5 deletions
diff --git a/drivers/md/dm-snap.c b/drivers/md/dm-snap.c
index b5b9118..5e553c5 100644
--- a/drivers/md/dm-snap.c
+++ b/drivers/md/dm-snap.c
@@ -1467,7 +1467,19 @@ static int snapshot_iterate_devices(struct dm_target *ti,
/*-----------------------------------------------------------------
* Origin methods
*---------------------------------------------------------------*/
-static int __origin_write(struct list_head *snapshots, struct bio *bio)
+
+/*
+ * If no exceptions need creating, DM_MAPIO_REMAPPED is returned and any
+ * supplied bio was ignored. The caller may submit it immediately.
+ * (No remapping actually occurs as the origin is always a direct linear
+ * map.)
+ *
+ * If further exceptions are required, DM_MAPIO_SUBMITTED is returned
+ * and any supplied bio is added to a list to be submitted once all
+ * the necessary exceptions exist.
+ */
+static int __origin_write(struct list_head *snapshots, sector_t sector,
+ struct bio *bio)
{
int r = DM_MAPIO_REMAPPED, first = 0;
struct dm_snapshot *snap;
@@ -1486,14 +1498,14 @@ static int __origin_write(struct list_head *snapshots, struct bio *bio)
goto next_snapshot;
/* Nothing to do if writing beyond end of snapshot */
- if (bio->bi_sector >= dm_table_get_size(snap->ti->table))
+ if (sector >= dm_table_get_size(snap->ti->table))
goto next_snapshot;
/*
* Remember, different snapshots can have
* different chunk sizes.
*/
- chunk = sector_to_chunk(snap->store, bio->bi_sector);
+ chunk = sector_to_chunk(snap->store, sector);
/*
* Check exception table to see if block
@@ -1543,7 +1555,8 @@ static int __origin_write(struct list_head *snapshots, struct bio *bio)
first = 1;
}
- bio_list_add(&primary_pe->origin_bios, bio);
+ if (bio)
+ bio_list_add(&primary_pe->origin_bios, bio);
r = DM_MAPIO_SUBMITTED;
}
@@ -1599,7 +1612,7 @@ static int do_origin(struct dm_dev *origin, struct bio *bio)
down_read(&_origins_lock);
o = __lookup_origin(origin->bdev);
if (o)
- r = __origin_write(&o->snapshots, bio);
+ r = __origin_write(&o->snapshots, bio->bi_sector, bio);
up_read(&_origins_lock);
return r;